During the manufacture of motor vehicles, a component is separated from a blank component in a separation procedure, and the components are assembled into a body, in particular through welding and/or adhesive bonding. The blank component is generally a metal sheet unwound from a roll. The components are fabricated or separated out of the blank component in a separation process by punching. After the components have been fabricated, i.e., punched out of the blank component, the component is formed, thereby giving the component its final shape. For example, forming takes place by bending or deep drawing.
The forming process is accompanied by expansion, and cracks arise at the edges of the component, i.e., edge cracks come about if the local expansion in the area of the edges is greater than a critical local expansion. The critical local expansion is the expansion which, when exceeded, gives rise to edge cracks of a specific size, e.g., edge cracks visible to the naked eye. The local expansion depends on the geometry of the component, i.e., on the geometry of the punching tools, and/or on the geometry of the shaping process, e.g., a radius of curvature of the component generated by bending, i.e., preferably on the geometry of the tools used in shaping. The local expansion depends on the component geometry prior to shaping, because the component geometry helps determine the local expansion in the shaping process, i.e., for example, the same geometry of shaping can result in varying local expansions at different positions of the component.
The punching tools for punching the various components out of the blank component are expensive to manufacture. For this reason, the components are first fabricated out of the blank component in a test run through laser cutting. Components made by laser cutting are used in a test run to shape the components and subsequently put together the components with varying geometries to yield the body. While manufacturing the components by punching them out of the blank component, the punching process causes micro-cracks to form on the edges and/or the edges to become brittle. For this reason, components fabricated by being punched out of the blank component already exhibit edge cracks at smaller local expansions than components made via laser cutting, i.e., the critical local expansion is smaller for components made by punching than for components made by laser cutting. When manufacturing a motor vehicle or body in a test or trial run with components fabricated by laser cutting from the blank component, no edge cracks can thus initially arise on the component that are larger than a specific value.
As final operations for manufacturing the body of the motor vehicle begin, the components are fabricated by punching them out of the blank component with punching tools. In this final and complete startup of the process for manufacturing the body for the motor vehicle, edge cracks can therefore arise on the edges after shaping that are larger than a specific value. Such edge cracks are unacceptable for the quality of the body, so that these edge cracks must be finished in a complex manner and/or the expensive punching tools must be changed out accordingly, so that shaping is performed with components having a different original geometry prior to shaping, so that the local expansion is smaller than the critical local expansion for components fabricated by punching them out of the blank component. This is especially disadvantageous, since finishing, for example by grinding the edges, after shaping results in high costs for manufacturing the body over the long run, and changing out the punching tools prior to startup is associated with high costs, because new, different punching tools produce high costs.
DE 10 2009 049 155 A1 discloses a device for manufacturing a test specimen out of a sheet metal material, wherein the test specimen to be fabricated exhibits at least one outer edge to be tested. The device encompasses a cutting tool, which can be used to generate at least one outer edge to be tested as a cutting edge with a defined cutting edge progression, and the device further encompasses at least one heater, which can be used to heat the sheet metal material in advance in a defined manner, at least in the area of such a cutting edge to be generated.
EP 1 785 940 B1 shows a computer-implemented method for quantitatively characterizing one or several geometric parameters of an edge crack in a part, which is subjected to a manufacturing operation. A window size is set for processing a selectable number of imaging data points that correspond to a starting segment of an edge in the part. The window is displaced for processing corresponding imaging data points that correspond to sequential segments of the edge. At least one of the segments exhibits an edge crack in the part; generating a line formed by several interconnected lines based on a line adjustment for each sequential segment of the edge; calculating a difference in pitch along the interconnected lines for each sequential segment of the edge. A first edge crack point is identified based on a change in a variable for the calculated difference in pitch. The first edge crack point points to a first curved bend in the edge crack. A radius of curvature is calculated to characterize the first curved bend and determine whether the calculated radius satisfies a specified minimal value.